IMAP access blocked

Hi there, my account was banned from IMAP access today. The only change I can recall is that I recently switched from Thunderbird to Outlook on my Windows machine. Apart from Outlook, I'm only using Apple Mail on my iPhone and my Mac. I'm pretty much unsure why this happened (connection limit?). I couldn't find a list of IMAP dos and don'ts. Can you please unblock my account and tell me why I was blocked?